Recently, the high integration of semiconductors has increased the processing and storage capacity of information per unit area. This has led to demands for large diameter semiconductor wafers, miniaturization of circuit line width, and multilayer wiring. In order to form a multi-layered wiring on a semiconductor wafer, high-level flatness of the wafer is required, and a wafer flattening process is required for such high-level flatness.
One of the wafer flattening processes is a wafer polishing process. The wafer polishing process is a step of polishing the upper and lower surfaces of the wafer with a polishing pad. The wafer polishing process is carried out using a polishing system having a polishing unit provided with an upper plate, a lower plate and a means for supplying polishing slurry to the polishing unit.
A pipe connected to the polishing unit for supplying the slurry to the polishing unit may be provided in the polishing system. However, the abrasive grains contained in the slurry may be adhered to the inside of the pipe to clog the pipe.
Furthermore, when such adhered slurry falls off and flows into the polishing unit, it may cause damage to the object to be polished and the polishing unit. Therefore, a solution to this problem is required.